// Copyright 2003-2005 Arthur van Hoff, Rick Blair
// Licensed under Apache License version 2.0
// Original license LGPL

package javax.jmdns.impl.tasks;

import java.util.Iterator;
import java.util.Timer;
import java.util.TimerTask;

import javax.jmdns.impl.DNSConstants;
import javax.jmdns.impl.DNSOutgoing;
import javax.jmdns.impl.DNSQuestion;
import javax.jmdns.impl.DNSRecord;
import javax.jmdns.impl.DNSState;
import javax.jmdns.impl.JmDNSImpl;

/**
 * Helper class to resolve service types.
 * <p/>
 * The TypeResolver queries three times consecutively for service types, and
 * then removes itself from the timer.
 * <p/>
 * The TypeResolver will run only if JmDNS is in state ANNOUNCED.
 */
public class TypeResolver extends TimerTask {

   /**
     * 
     */
   private final JmDNSImpl jmDNSImpl;

   /**
    * @param jmDNSImpl
    */
   public TypeResolver(JmDNSImpl jmDNSImpl) {
      this.jmDNSImpl = jmDNSImpl;
   }

   public void start(Timer timer) {
      timer.schedule(this, DNSConstants.QUERY_WAIT_INTERVAL, DNSConstants.QUERY_WAIT_INTERVAL);
   }

   /**
    * Counts the number of queries that were sent.
    */
   int count = 0;

   public void run() {
      try {
         if (this.jmDNSImpl.getState() == DNSState.ANNOUNCED) {
            if (count++ < 3) {
               DNSOutgoing out = new DNSOutgoing(DNSConstants.FLAGS_QR_QUERY);
               out.addQuestion(new DNSQuestion("_services._mdns._udp.local.", DNSConstants.TYPE_PTR,
                        DNSConstants.CLASS_IN));
               for (Iterator iterator = this.jmDNSImpl.getServiceTypes().values().iterator(); iterator.hasNext();) {
                  out.addAnswer(new DNSRecord.Pointer("_services._mdns._udp.local.", DNSConstants.TYPE_PTR,
                           DNSConstants.CLASS_IN, DNSConstants.DNS_TTL, (String) iterator.next()), 0);
               }
               this.jmDNSImpl.send(out);
            } else {
               // After three queries, we can quit.
               this.cancel();
            }
         } else {
            if (this.jmDNSImpl.getState() == DNSState.CANCELED) {
               this.cancel();
            }
         }
      } catch (Throwable e) {
         this.jmDNSImpl.recover();
      }
   }
}